Automatic engine control



May 16, 1939- M. s. CURTIS 2,158,572

AUTOMATIC ENG I NE CONTROL Filed Feb. l, 1933 77e, di

BY M um 7 ATTORNEY Patented May 16, 1939 UNITED STATES PATENT lOFFICEMyron S. Curtis, Pawtucket, R. I., asslgnor to William Wallace Potter,Pawtucket, R. I.

application February 1, 1933, serial No. 654,724

Claims;

-As a satisfactory exempliiication of my invention, I will take the caseof an internal combustion engine which usually has a carburetor forfurnishing an explosive mixture to the engine.

5 This carburetor is commonly furnished with an air admission, or, as itis usually called, a choke valve, for regulating the amount of airsupplied to the carburetor, which regulation is necessary to provide a.proper mixture, and a throttle valve )0 for regulating the amount ofmixture supplied to the engine, and hence the speed of the same.

The engine is also commonlysupplied with a starting motor and a manuallyoperated switch to f control it for cranking the engine.

There is. a certain nicety of control necessary in starting an engine,particularly if it is cold, and in keeping it nmning until it is warmed"up. The operator must properly manipulate the choke and throttle valves,while operating the cranking motor, and this manipulation is beyond theability of the average driver. The result is that the engine is eitherflooded, or too rich a mixture is used resulting in washing thelubricating oil from the engine walls at the time when it is mostnecessary and in crank case dilution, or the engine stalls due to leanmixture or improper Y throttle opening, and the operation of the engineis in general unsatisfactory until it is warmed up.

Also with the present day multi-cylinder engines an with small flywheelinertia, there is danger of the engine stalling while idling, thisdanger being particularly prevalent with free wheeling, and with presentdesign engine noise has been so far eliminated that often the iirstknowledge the operator has of a-stalled engine is its failure to pick upspeed when he opens the throttle.

It is therefore, desirable that the operation of adjusting the choke andthr'ottle valves for a proper mixture, and the operation of the self- 40starter, be removed as far as possible from the necessity of operatorcontrol, that is to say, that the engine will be always running and keptrunning with the proper mixture as long as the ignition switch is on,and will remain stopped when the ignition switch is off.

There have been separate devices invented for controlling the mixture,and for starting the engine. My invention combines into one unit, `the lcomplete control of mixture, anti-stall, and starting, and I accomplishthis control by a combination of intake, manifold pressure, mixturetemperature, and throttle opening, which three conditions, as will behereinafter explained, are those to be considered for a proper operationof the engine.

(Cl. 29o-37) By my invention, provision is also made automatically tomake operation of the starting motor impossible under conditions whichwould be hurtful or otherwise objectionable, as for example, when theengine is running, when it is en- 5 gaged with its driven member vorwhenthe ignition timing is so far advanced as to present the danger ofpre-ignition when starting, with the consequence that the engine willrun backwards.

I do not restrict myself to an embodiment of 10 my invention which willcontain al1 or any number of the features or the devices beforementioned or hereinafter to be described, but my invention is to beunderstood as consisting in whatever is described by or is includedwithin the l5 terms or scope or legal meaning of the appended claims. I

Referring to the drawing, which for the purpose of clarity ofillustration, is somewhat diagrammatical,

The figure is an elevation of enough of a gas engine to illustrate anembodiment of my invention.

I illustrate my invention as applied to a carburetor I0, of theso-called downdraft type, and 25 which is bolted to the intake manifoldII, from which the mixture flows to the` engine. Air enters thecarburetor through port I2, the amount of air supplied being controlledby the choke valve I3, which is shown of the balanced butter- 30 flytype. It may, however, be of any type. The suppy of mixture from thecarburetor to the engine is controlled by the throttle valve I4, whichis manually operated in the usual manner. Fuel is fed to the carburetorfrom a. float chamber 35 through jets in the ordinary manner. As themethod of feeding fuel forms no part of my invention, the float chamberand jets are not illustrated.

The choke valve I3 is fastened to a shaft I5 to 40 the squared end ofwhich is fastened the choke lever I6. The valve is normally held closedby coil spring I'I, one end of which is fastened to lever I6 and theother end to the carburetor body. Choke valve I3 is opened by, andaccord- 45 ing to the degree of engine suction, the motion of an enginevacuum actuated diaphragm I8` transmitted by diaphragm rod I9 to a pin2U fixed on lever I6. The diaphragm is held on rod I9 by flanges 2I and22, nut 23 and collar 2l, the l0 latter serving as a limit stop byabutting the adjacent end wall 25 of the diaphragm chamber when thediaphragm is moved to that position by spring 26, when there is noengine vacuum. The diaphragmis tightly clamped' at'its outer rim at apoint between wall 25 and the opposite end wall 21, and the spacebetween the latter and the diaphragm is connected by pipe 28 with thecarburetor or intake manifold on the enigne side of the throttle so thatthe vacuum acting on diaphragm I8 is that existing in the intakemanifold.

A lever 29 is pivoted on stud 30 fast in body I0 and .has an arm 3|encircling rod I9, and which arm is held against stop pin 32 by spring33. The other arm 34 of lever 29 has a slip joint connection withthrottle arm 35, by means of the rod.

36 being longitudinally slidable in holes in one end of link 31 andhaving a stop collar 38 on this end. An adjustable connection isprovided between rod 31 and throttle arm 35 by means of a threaded rod39 screwed into the other end of link 31'. With this slip jointconnection, it is apparent that rotation of lever 29 in a clockwisedirection can move arm 35 to open the throttle I4, but/the throttle isfree to open or close beyond this position without affecting lever 29.

Rod 36 has slidably mounted upon it flanged sleeve 40 held by spring 4|against the end of arm 42 of choke lever I6 spring 4| being of suchlength that with choke valve I3 closed and throttle I4 slightly openedsleeve 40 will approximately touch arm 42. The length and strength ofspring 4| is varied to suit different carburetors. Throttle lever 35 isprovided with the customary stop 43 and stop screw 44.

For controlling theposition of choke valve I3, according to mixturetemperature, I provide a thermostat 45, which is preferably of thebimetal coil spring type, although I do not limit myself to this type,and which I have shown with the outer end 46 in intimate contact withthe intake manifold casting so that the'position of the thermostat arm41 reects the temperature of the mixture. However, the thermostat can belocated at any desired place. The other inner end 48 of the thermostatcoil is fastened to shaft 49 to which is fastened arm 41, and thethermostat coil is so arranged that heating it causes arm 41 to move ina clockwise direction. I preferably shroud thermostat 45 with a cover 50which in this case I have designed to provide also a support for theshaft 49 and a means. for clamping the thermostat to the intakemanifold. Arm 41 is connected by rod and adjustable connection 52 withlever 53 pivoted on stud 54. A stop pin 55 limits movement of lever 53in a counter-clockwise direction. A pin 56 on lever 53 coacts with jawface 51 of lever I6 to provide "a yielding stop against opening movementof choke valve I3, when the thermostat is cold, the position of pin 56,and hence the degree of resistance to opening, depending on thetemperature of the thermostat. When the thermostat becomes hot pin 56coacts with jaw face 58 of lever I6 and forms a positive stop againstthe closing of choke valve I3.

Rod I9 has a lug 64 which upon movement of rod I9 to the right underaction of intake suction, engages the free end of a spring leaf 65, onwhich is an electric contact point 66 that by coaction with a contactpoint 61 on spring leaf 68 makes and breaks a circuit.' These twocontacts are held together by the tension of the two spring leaves. Thisadds yielding resistance to the movement of rod I9, and further movementof said rod to the right moves leaf 65 away from leaf 68, but due to itsspring tension leaf`68 will follow leaf 65 until it strikes anadjustable stop screw 69, when its motion will end and contact betweenpoints 66 and 61 will be broken bythe further movement of leaf 65.Similarly, move- Driven by the engine 83 is a generator 84l equippedwith the usual battery cut out 85, which prevents current flowing backfrom the battery through the generator and also prevents the generatorfrom charging the battery until the voltage has reached a predeterminedvalue. The generator 84 is electrically connected through this batterycut out and by wires 86 and 81 with a storage battery 8B, and thisbattery is also electrically connected by wires 81, |0|, 89, 90 andswitch 8| with starting motor 9| so that when switch 8|, which isnormally held open by spring 82, is closed by current being supplied tosolenoid 12, the starting motor is operated, thus cranking the'engine.

Solenoid 12 is electrically connected with battery 88 through wire 13,spring leaf 68, contacts 61 and 66, spring leaf 65, wire 19, ignitionswitch |14, wire 80, timing switch |02, wire |03, reversing switch |04,thence to solenoid switch |15, either through wire |05, gear leverswitch 19 and wires 92 and 93, or through wires"|05 and 94, clutchswitch 18, and wires 95 and 93, and from switch |15 to battery 88,through Wires |00 and 81. Ignition switch |14 is operated manually tostart the engine. Timer switch |02 is normally held closed by spring|06, but may be opened by finger |01 fastened to the inner head |08.This timer head is customarily rotated either by hand or automaticallyto advance or retard the spark, the rotation to advance the spark beingin the direction shown by the arrow. It is therefore apparent thatadvancement of the spark beyond a predetermined point will open switch|02. Reversing switch |04 is of the well known type where the switch bar|04 is frictionally connected through disc |09 with a rotating part ofthe engine, which normally rotates in the direction shown by the arrow,so that the switch is frictionally held closed when the engine isrotating in its normal direction, and is held closed by gravity when theengine is stopped. Reversal of the rotation of the engine, however,opens switch |04 by friction disc |09, the degree of openingbeinglimitedby stop pin ||0. Switch 19 is so operated by the gear shift lever 96that it is closed when the gears are in neutral and at other times isopen and switch 18 is so operated by the clutch pedal 91 that it isclosed when the clutch is disengaged and open when the clutch isengaged. Switch |15 is normally held closed by the spring |16, and maybe opened by a solenoid 11, which latter takes current from generator 84through wires 98 and 99. When the engine is running and the generator isfurnishing current, solenoid 11 is excited by this current and opensswitch |15 against the resistance of spring |16, so that switch |15 isopen when the engine is running. Thus when contacts 66 and 61 aretouching, ignition switch |14 is closed, timer switch |02 is closed,reversing switch |04 is closed, switch |15 is closed, and either switch18 or switch 19 is closed, an electrical circuit is formed throughsolenoid 12, closing switch 8| and operating the starting motor, butopening any of these switches will break the current, thus allowingswitch 8| to open. I do not limit myself to a structure that containsall these switches, for instance, any or all of switches 11, 18, 19,|02,

|94 and |15 may be omitted from the control clrcuit.

As hereinbefore described rod I9 is free to slide in arm 3| of lever 29,but continued movement of the rod to the right under action of intakesuction and against the pressure of spring 26 causes lug 63, on rod I9,to engage arm 3| so that further movement to the right of rod I9 moveslever 29 counter-clockwise and also brings spring 33 into cooperationwith spring 26 to resist movement of rod I9.

I will now describe briefly, the operation. The throttle stop screw 44is adjusted with relation to stop 43 to give the desired idling speedwhen the engine is hot, and connection 39 is adjusted so that when leverarm 3| abuts stop pin 32 the throttle is open considerably more than atnormal idling speed. Assume the engine stopped and cold, then lever 53is held against stop 55 by thermostat 45. As there is no vacuum in themanifold, rod I9 is held by spring 26 in its extreme left position withcollar 24 against chamber wall choke valve I3 is held shut and spring 33holds arm 3| against stop 32 and, thus by rod 36, collar 39, link 31 andconnection 39, holds throttle I4 open, with the contacts 66 and 61touching, all as illustrated.

As the engine is stopped, switch |04 is closed and if the spark isproperly retarded switch |02 is closed. u

The ignition switch |14 is now closed by the operator. With the enginestopped, no current flows through solenoid 11, and switch |15, is,therefore, closed by spring |16. If either the clutch is out, thusclosing switch 19, or the gears are in neutral thus closing switch 19, acircuit is formed through solenoid 12, when contacts 66 and 61 touchthus closing switch 9|, energizing the starter motor 9| which cranks theengine; but if both the clutch is in and the gears engaged, no circuitwill be made, and the cranking motor will not be started. The crankingof the engine causes a low vacuum in the intake manifold whch iscommunicated through pipe 29, to the diaphragm and thereby overcomes theresistance of spring 26, moving rod I9 to the right until lug 64 abutsspring leaf 65, the extra resistance of this spring leaf preventingfarther movement of rod I9, as the low vacuum is not enough to overcomethis extra resistance. This 'Y movement of rod I9 to the right tendsthrough spring 62 and pin 20 to move lever I6 counterclockwise, thusopening the choke and, as there is a slight amount'of play between pin56 and jaw face 51, a slight opening is obtained before thermostat lever53 begins to offer resistance. At cranking speed, the movement oi'diaphragm I9 will tend to be intermittent due to the alternate suctionand compression strokes of the engine pistons, hence choke valve I3 willhave a slight utter. When the engine is very cold the thermostat holdslever 53 hard against its stop pin 55, and pin 56 offers so muchresistance to movement of lever I6 that spring 62 is compressedand thechoke opens but slightly. If the engine is warmer, however, lever 53offers less resistance to movement of ,arm I6 and spring 62, either doesnot compress at all, or but slightly, thus giving a greater chokeopening for cranking when the engine is warm than when it is very cold.Thus regulation of the cranking opening of the choke valve isaccomplished by vthe degree of antagonism between thermostat lever 53and spring 62.

Immediately the engine starts firing, the firing vacuum (which is muchgreater than the starting vacuum) is enough to overcome the resistanceof spring leaf 65, and the rod I9 is moved farther to the right,breaking contacts 66 and 61, thus cutting out the starting motorcircuit. also provide for breaking the starting motor circuit when theengine begins ilring by solenoid 11, which is energized by the generatorvoltage when the engine starts firing, and thus opens switch |15. 'I'hismovement of rod I9 also opens the choke still more, the amount ofopening depending upon the degree of vacum and the resistance which thethermostat offers through arm 53 and pin 56 to the movement of lever I6,this resistance being greater the colder the engine. If the engine iswarm at starting the thermostat offers but little resistance, and if itisl at its normal running temperature the thermostat has rotated lever53 sulciently clockwise to hold the choke valve positively wide open.

After the engine has been started the idlingvacuum in the chamber 21,when the engine is idling, is enough to overcome the resistance ofspring 33, by lug 63 coacting with arm 3|. This rotates lever 29counter-clockwise, thus allowing throttle I4 to close toward its normalidling position from starting position, the degree of closure dependingon the temperature through the resistance oiered by thermostat arm 53.Thus, the idling speed with a cold engine will be greater than that witha warm or hot engine.

When the throttle is operated manually to increase the engine speed,opening the throttle causes the vacuum to suddenly drop temporarily.This allows the choke valve to close as the rod I9 will move to the leftto permit lever I6 to move clockwise depending on the condition of thethermostat 45, which action may give too rich a mixture. However, as thethrottle is opened, sleeve 40 is pushed by spring 4| against arm 42 onlever I6 tending to move it anti-clockwise to open the choke, and thusovercome the eiect due to the vacuum drop. This opening of the chokebeing resisted by thermostat arm 53, it will be seen that a properrunning mixture is attained through the co-operation of intake manifoldpressure, engine temperature and throttle opening, and none of theseelements can be left out of consideration andfstill have a propermixture. The temporary lowering of the vacuum by opening the throttlemay allow rod I9 to move far enough so that lug 64 will no longer holdcontacts 66 and 61 apart. To prevent their closing under this conditionand thus operating the starting motor, sleeve 40, when the throttle isopened, moves finger 14 counter-clockwise and, by lug 16 on iinger 14,holds contacts 66 and 61 apart. It will thus be seen that the startingmotor cannot be energized while the throttle is open and unless thevacuum is less than the firing vacuum.

If the engine while idling either hot or cold tends to stall, the vacuumimmediately drops to a degree where diaphragm I9 is unable to overcomethe resistance of spring 33, which immediately rotates lever 29,clockwise, thus opening the throttle valve and preventing stalling.

If the operator has before starting the engine, advanced the spark to apoint where there is danger of the engine reversing upon starting,switch |02 is opened by finger |01 on timer head |09, thus breaking thestarting circuit, or if the engine does reverse upon starting, switch|04 is opened by friction disc |09, breaking the starting circuit. Y

lli)

What i claim is:

i. An internal combustion engine having an intake manifold, a throttlevalve and ignition means including a switch for the latter, a' startermotor for the internal combustion engine, means controlling the runningof the starter motor and operation of said throttle valve sequentiallyby variations in pressure in the intake manifold of the engine caused byoperation of the latter, a generator driven from the engine, and meansindependent and separate from said pressure actuated controlling meansand affected in its operation by the amount of voltage generated by saidgenerator for rendering said starter motor ineffective when thegenerator produces a voltage and upon drop of said voltage the startermotor control means is placed in condition for effective operation ofthe starter motor by the aforesaid variation in manifold pressure.I

2. An internal combustion engine having a starting motor, a valve whoseposition affects the fuel to the engine, means for operating said valve,means controlling the operation of said starting motor and operativelyconnected with the valve, means making the operation of the valveoperating means dependent upon the intake manifold pressure, comprisingan element acted upon by such pressure .whereby said valve operatingmeans is automatically actuated, means responsive to engine temperaturethat affect the automatic operation of the valve operating means, saidvalve operating means being such that it may be manually operated toopen said valve irrespective of its automatic operation, and manualmeans to modify the automatic action of the said last two mentionedmeans 'and actuating said starter control means to stop said startingmotor.

3. An internal combustion engine having a starting motor, a carburetorhaving a choke valve and a throttle valve, valve moving means, an intakemanifold pressure receiving element movable in one direction by suchpressure and controlling said valve moving means, a plurality, ofyielding resistances, an operative connection between each of the latterand said valve moving means, said resistances being arranged forsuccessive action, and means for controlling the operation of saidstarter motor and arranged with respect to the valve moving means to beactuated by the latter for rendering the starter motor ineffective, whenthe engine is self-propelled, and for rendering the starter motoroperative when the manifold pressure on the pressure receiving elementis less than that produced by the normal self propulsion of the engine.Y

4. An internal combustion engine having an electric starting motor, acarburetor, a choke valve, a throttle valve, an electric circuit thatincludes the motor, a normally open starting switch in such circuit, acontrol circuit for operating said starter switch, an automaticallyoperable normally closed switch in said control circuit, means to openthe normally closed switch comprising a to and fro movable elementsubject to intake manifold pressure that is adapted to cause movementsin the direction to open said normally closed switch, and operativeconnections between said member and said valves.

5. An internal combustion enginehaving an electricv starting motor, acarburetor, a choke valve, a throttle valve, an electric circuit thatincludes the motor, a normally open starting switch in such circuit, acontrol circuit for operating said starter switch an automaticallyoperable normally closed switch in said control circuit, means to openthe normally closed switch comprising a to and fro movable elementsubject to intake manifold pressure that is adapted to cause movementsin the direction to open said normally closed switch, and operativeconnections between said member and said valves, including in the caseof the choke valve temperature responsive means that controls the extentof opening of the choke valve, whereby such valve opens more when theengine is warm than when it is cold.

6. An internal combustion engine having a starting motor, means to putthe motor at Work, a carburetor with a choke valve, engine-operatedmeans that include a to and fro moving member subject to intake manifoldpressure, a lever fixed to the choke valve, an operative connectionbetween said member and lever, a stop for said lever movable relative tosaid lever, a thermostat operatively connected with said stop to move itrelative to the lever, and means to stop the starting motor including anelement movable to starting motor stopping position by said member.

7. An internal combustion engine having an electric starting motor, acarburetor, a choke valve, a' throttle valve, an electric circuit thatincludes the motor, a normally open starting switch in such circuit, acontrol circuit for operating said starting switch, an automaticallyoperable normally closed switch in said control circuit, means to openthe normally closed switch comprising a to and fro movable elementsubject to intake manifold pressure that is adapted to cause movementsin the direction to open said normally closed switch, and operativeconnections between said member and said valves, a generator actuatedfrom the engine, another normally closed switch in said control circuit,and means actuated by the voltage generated by said generator foropening said other switch, saidv other switch closing upon the drop involtage produced by the generator.

8. In a vehicle, the combination of an engine, a fuel intake, a throttlevalve in the fuel intake and normally positioned to furnish more than anidling fuel supply, a-starting motor and a control circuit therefore, anormally closed switch in said control circuit, whereby upon furnishingcurrent to said circuit, said starting motor will operate; anengine-operated means for moving said throttle to an idling fuel supplyposition, said engineoperated means including means for opening saidswitch 4prior to the movement of said throttle to idling fuel position.

9. In a vehicle the combination set forth in claim 8 furthercharacterized by a manually operable means for actuating said throttle,and means actuated by the manual opening of the throttle to preventactuation of said starting motor.

10. In a vehicle, the combination as set forth in claim 8 furthercharacterized by the engine actuated means being a device responsive topressure variations in the engine manifold, manually operable means toactuate said throttle for accelerating the engine, and means for openingsaid Switch upon the manual operation of the throttle and to preventclosing thereof by the pressure responsive means due to pressurevariations upon acceleration of the motor.

MYRON S. CURTIS.

